Carpet stretcher improvements

ABSTRACT

A hand powered carpet stretcher is provided with the improvement of ratchet means to permit locking of the stretcher head at any of a plurality of extensions with remote actuation means to lock the ratchet so that the stretcher can be operated with a single handed motion. In one of the embodiments, the ratchet lock means is automatically engaged or disengaged upon movement of the handle of the stretcher.

United States Patent Payson [451 Sept. 26, 1972 [54] CARPET STRETCHER 1,929,837 10/1933 Cathcard ..254/$9 IMPROVEMENTS 3,266,772 8/1966 Francis ..254/63 3,441,252 4/1969 Koppelmans ..254/61 (72] inventor: Buford L. Payson, Garden Grove,

Calif- Primary Examiner-Othell M. Simpson [73] Assignec: Robert E. Strauss, Orange, Calif.' a A"0mey Rben Strauss part Interest 57] ABSTRACT [22] Flled: 1971 A hand powered carpet stretcher is provided with the [21] A l. No.; 173,779 improvement of ratchet means to permit locking of the stretcher head at'any of a plurality of extensions with remote actuation means to lock the ratchet so US. Cl. th t th t t h can b p t d a i gl Int. Cl. handed motion In one of the embodiment the [58] Field Of Search ..254/5763 ratchet lock means is automatically engaged r disem gaged upon movement of the handle of the stretcher. [56] References Cited UNITED STATES PATENTS 12 Claims, 15 Drawing Figures 266,893 10/1882 Risdon ..254/63 PATENTEDsEP2s m2 SHEET 1 BF 4 FlGUQE FIGURE 4 FIGURE 2 74 BUFORD L, PAYSON IN VENTOR.

F \GURE 5 ATTORNEY PATENTEDSEP26 m2 3,693,936

SHEET 2 BF 4 FIGURE 8 INVENTOR.

FIGURE 6 BYBURD LPAY'SON ATTORNEY PAIENIEDSEPZB I912 1693.9 36

SHEET 3 BF 4 FIGURE \2 FIGURE 9 F'IGUQE IO INVENTOR. BUFORD L. PAYSON AT ORNEY PATENTEDsrrzs m2 sum u or 4 FIGURE FIGURE l5 INVENTOR.

BUFORD L. PAY SON BY CARPET STRETCHER IMPROVEMENTS DESCRIPTION OF THE INVENTION This invention relates to carpet installation equipment and, in particular, relates to improvements in carpet stretchers which greatly expand the versatility and usefulness of the stretchers.

Carpet stretchers commonly comprise a tail block that bears against a wall, a pole extension with one end fitted into the tail block and a power unit on the opposite end, the latter element being a hand operated unit having a lever that furnishes a mechanical advantage to the operator. The power unit includes a head that has teeth which grip the carpet attached to a shaft which telescopes into the pole extension. A lever is pivoted on the head and is attached to the pole extension by a pivotable link so that the head is forced forward when the handle is depressed and retracted when the handle is raised.

The conventional stretcher only permits locking of the head at its furthermost extension when the lever has been folded against the pole and the link has thereby been moved slightly past a parallel alignment with the pole and lever. As the lever (handle) moves past this parallel alignment, the head retracts slightly and some of the tension on the carpet is released. A considerable degree of skill is required in the initial positioning of the head to the carpet so that the proper degree of tension is applied to the carpet exactly when the head is fully extended and locked. This requiresa pumping of the handle with frequent resetting of the teeth in the carpet even by expert carpet installers to obtain exactly the right bite before the handle is locked down.

A need exists for a unit that provides a more flexible adjustment in the carpet tension when the stretcher is in the locked position and this need has been recognized by a number of devices that have been proposed. One stretcher that has been proposed provides a variable positioning of a pawl between the handle and the pole extension so that when the handle is fully depressed, the head can be at various extensions. This approach is shown in US. Pat. No. 3,441,252. This unit still requires complete depressing of the handle to lock the head extension and, furthermore, sacrifices the powered retraction of the head.

Another approach that has been introduced to the market has a sliding collar on the head shaft which can be tilted to the shaft and bind the shaft against telescoping into the pole extension. This unit, however, requires use of both hands by the operator to lock or unlock the head. The device is substantially more cumbersome and bulky than the conventional power unit and has received only a limited acceptance in the trade.

Another unit which has not found acceptance in the trade departed entirely from the desirable lever linkage found in the conventional power stretcher and employs a fixed and movable rack driven by a pinion attached to the handle. This is shown in US. Pat. No. 1,929,837 as requiring a bulky and complex mechanism.

The prior attempts to provide a power stretcher with a locking variable extension of the head have failed to retain the desirable strength, lightness and singlehanded operability'of the conventional power stretcher and have sacrificed one or more of these characteristics to achieve variation in the locked position of the stretcher head.

It is, therefore, an object of this invention to provide a power stretcher with means to lock the head thereof at any of many extensions.

It is also an object to provide such means without sacrifice of the strength or lightness of the stretcher.

It is a further object to provide such means with remote control of the lick means at the handle to permit single-handed operation of the stretcher.

It is an additional object to provide such means which can be operated in the conventional manner at the preference of the operator or in the event of failure of the lock means.

It is a still further object of the invention to provide such means in the form of a kit that can be fitted to the many power stretchers presently in use without any substantial modifications thereto.

It is an object of a preferred embodiment to provide a variable and extendible attachment of a power unit to the stretcher pole assembly.

It is an object of another preferred embodiment to provide a plate and teeth casting having superior strength and simpler construction than the conventional plate and teeth assembly.

The aforementioned objects are attained by this invention which comprises a hand powered stretcher unit having ratchet means in one of the movable joints of the power unit with pawl means carried by the mating member of such joint in a position permitting the movement of the pawl means into and out of engagement with the ratchet means with pawl actuation means linking the pawl means to the lever of the power stretcher whereby the pawl means can be moved into and out of engagement with the ratchet means by a single-handed movement of the lever. In one of the embodiments, the pawl actuation means is automatically engaged when the lever is depressed and is automatically disengaged when the lever is raised. The objects of the various preferred embodiments are achieved by a unique sliding collar lock between the power unit and the pole extensions and by a method for casting the teeth and head plate as a unit, thereby simplifying the fabrication and also increasing the durability of the unit.

The invention will now be described by reference to the FIGS., of which:

FIGS. l-3 illustrate a power head unit of the invention with an external ratchet mechanism and a collar lock between the unit and the pole extension;

FIG. 4 illustrates a modification of a conventional power unit to incorporate a ratchet unit in the stretcher handle;

FIGS. 5 and 6 illustrate a unit having an independent ratchet rod;

F IGS. 7 and 8 illustrate a unit with an internal ratchet rod and an automatic ratchet release;

FIGS. 9 and 10 illustrate another ratchet and housing assembly;

FIG. 11 illustrates the components that can be used to modify conventional carpet stretchers;

FIGS. 12-14 illustrate a preferred head assembly; and

FIG. 15 illustrates a sliding lock assembly between the unit and its pole extension.

Referring now to FIG. I, the unit is shown with a head 10 having pins 12 which can be engaged in a carpet and being assembled to an elongated tube 14. This tube is in sliding connection with the base member 16 in a telescoping joint and an end of lever or handle 18 is pivotably connected to head assembly 16 by pin 20. The handle is fulcrumed by link member 22 which is pivotably attached to an intermediate point on the handle by pin 24. The opposite end of link 22 is pivotably connected to the base member 16 by pin 26 which extends through bracket 44, secured by screw 46.

Ratchet means in the form of rack 28 is cut into tube 14 along its sliding connection with base 16. The base supports a pawl 30 which can be actuated by cable 32 between an engaged and disengaged position with rack 28. The cable extends to the handle 34 that is supported on the free end of handle 18 to a connection to lever 36. Pawl 30 is shown in FIG. 4. I

Considering the structure in greater detail, the base comprises a tubular member 48 which has a diameter to mate with the tube extension commonly used in carpet stretcher assemblies. These are usually steel tubes that fit together. Thelarger tubes are 1.785 inches outside and 1.645 inches inside diameter and the smaller tubes which fit within the larger tubes are 1.625 inches outside diameter and 1.495 inches inside diameter in a typical assembly. These tubes are interlocked with spring biased buttons that fit into apertures of the mating tube.

At a point intermediate its length, bracket 44 is attached to tube 38 by a welded or bolted connection. Preferably, this attachment is reinforced by a short sleeve 42 that fits within tube 38 and a screw 46 is extended through the base or web of bracket 44, tube 38 and into engagement with a tapped bore in sleeve 42.

The fore end of tube 38 is slipped over acast housing 48 which has a peripheral rim 50 that serves as a stop for tube 38. Cast housing 48 is generally tubular and a sleeve 52 is fitted into its central longitudinal opening to serve as a bearing sleeve for telescoping tube 14. Tapped bores can be provided in the cast housing and/or sleeve 52 and cap screws 33 can be engaged into these bores to retain the assembly. The forward end of sleeve 52 can project slightly past the end of housing 48 as shown to aid in retaining axial alignment of tube 14. Sleeve 52 can be formed of brass or other material having adequate strength and a low coefiicient of friction to provide a bearing surface for tube 14. It is preferred, however, to provide another short sleeve 53 within tube 38 and this sleeve can be fitted with anv inner bronze bearing. This short sleeve or collar can provide most of the bearing support for tube 14 and sleeve 52 can then be formed of steel. This collar 53 can also be retained by cap screws such as 33.

Referring now to FIGS. 2 and 3, the latch mechanism can be seen in greater detail. The fore end of casting 48 has a flat bottom 54 and an offset shoulder that extends along one side of the fore end of this housing. A bore 58 extends through this shoulder substantially parallel to the central longitudinal opening of the casting. The bottom of the cast housing has a slot 56 which extends into the central bore of the housing and which is centrally positioned immediately forward of rim 50 and this slot extends through sleeve 52. One side of the housing has another slot 60 which has a sufficient depth and which extends upwardly sufficiently to intersect bore 58.

A rod 62 is fitted into bore 58 and through the upper end of slot 60 to terminate in bore 58, rearwardly of slot 60. Resilient means such as spring 64 is secured to the end of rod 62, e.g., by passing through a bore in the end of this rod and the opposite end of the spring is secured in the bore by pin 66. Rod 62 has a flat face 68 milled onto its surface to provide shoulders 69 and 70 at a point along its length which is in slot 60 of the housing 48.

Pawl 30 is supported in slot 56 by shaft 72. Housing 48 is bored transversely at 74 and shaft 72 extends through this bore. The outboard end of shaft 72 projects into slot 60 and supports lever 76 which extends upwardly between shoulders 69 and 70. The pawl 60 and lever 76 are rigidly connected to shaft 72, e.g., by a welded joint so that movement of lever 76, which is effected by movement of rod 62, rotates pawl 30 into and out of engagement with rack 28. Spring 64 and cable 32 control the movement of lever 76 and pawl 30, e.g., spring 64 can be under tension to urge pawl 30 into engagement and cable 32 can retract pawl 30 from engagement with rack 28.

The maximum travel of shaft 14 in sleeve 52 is limited by an internal stop. This can be achieved by various means, however, a preferred means is longitudinal slot 78 that extends along one side of shaft 14. A pin, not shown, is fitted into a tapped bore in the side of housing 48 and this pin projects into the slot to serve as a stop when the end of the slot 78 encounters the pin. A stop of this construction is described in greater detail hereinafter with regard to FIG. 8.

An optionaland preferred construction is shown in FIG. 1 which employs an adjustable connection between the base member 16 and the tube extensions commonly used in carpet stretcher assemblies. The common method of attachment is to use apertures in tube 38 such as are shown in tube 100 of FIG. 4. These apertures mate with spring biased buttons that are supported at the ends of the tubes and that will lock into the apertures in the tube extension of the power unit. There are usually three apertures at 2 inch spacings to permit extension of the head at two and four inch intervals. Frequently, however, incremental spacings other than two and four inches are desired. In addition, resetting of the buttons into another set of apertures can be difficult.

Accordingly, it is preferred to place an adjustable lock between the base member 16 and the stretcher tubes 17. Such a lock is shown in FIG. 1 wherein the tube 17 is fitted with a tube or shaft 19 which has a diameter to permit its telescoping into tube 14. Tube 38 carries two collars, 21 and 23, which fit about tube 19. Collar 21 is secured in tube 38'by pin 25 while collar 23 fits loosely in tube 38 at an angle thereto of about 70 to Collar 23 has a finger 27 which projects through an aperture in tube 38. Another aperture is provided on the opposite side of tube 38. Lever 29 passes through this aperture and is secured to collar 23.

A spring 13 is placed between collars 21 and 23. A larger diameter spring than shown can be used which will surround shaft 19, however, it is preferred to use the smaller spring as illustrated. Whenever it is desired to extend the base member 16 on shaft 19, lever 29 can be moved rearwardly against the bias of spring 13 and the base member pulled forward, e.g., by lifting lever 18 or by pulling the entire power unit forward. When lever 29 is released and compressive loading is applied by moving lever 18 downwardly with pins 12in the carpet, collar 23 will securely lock against shaft 19.

Any of the conventional stretcher heads can be used in the assembly. The particular head illustrated has a preferred construction that insures that the head retains the proper attitude when tension is applied to the carpet and that also provides a shorter overall length to the stretcher. The details of a head of closely related structure are set forth in a discussion of FIGS. 12-14 and are not repeated in this discussion of FIG. 1. Briefly, however, the head comprises a cast plate of aluminum or similar metal with teeth 12. The plate is connected to adapter 79 at its mid-line by a joint which permits the head to swivel and lever 82 is used to lock the plate to the adapter. Tube 14 is secured to adapter 79 at its base and handle 18 is pivotably attached to the adapter by pin 20.

An alternative ratchet and pawl means is shown in FIG. 4. In this unit a conventional tail tube 100 is used that has link 102 pivotably attached to the tube by a bracket 104. Preferably, link 102 is a single member that is positioned on the longitudinal mid-line of the unit. The handle has an inverted U-shaped cross section with side webs'of sufficient dimension to provide space for the ratchet and pawl assembly. When the handle is fully depressed, its side webs extend past link 102 and over tube 100 to provide a very compact unit.

Ratchet means in the form of an arcuate rack 106 is attached .to the fore end of link 102 by suitable means, e.g., screws 108, at a position such that the center of radius of the arcuate rack is at pin 110 which links the lever 112 to the link 102. Pawl means 114 is pivotably mounted in the handle by pin 116 which is supported by one or both side webs of handle 112. The pawl is rigidly secured to lever 118 which also pivots on pin 116 so that the pawl 114 can be moved into and out of engagement with the rack 106 by movement of lever 118. The upper end of this lever is bored to receive one end of rod 122 and one end of spring means 124. Preferably, spring 124 is under tension to urge the pawl into engagement with rack 106 and movement of the rod will retract the pawl from such engagement. However, it is apparent that a compression spring could also be used to retract the pawl and the rod could force the pawl into engagement with the rack against the bias of the spring. The rod extends along handle 112 to a point adjacent the hand grip at the end of the handle and the end of the rod is attached to a lever such as 36 shown in FIG. 4.

The arcuate rack 106 provides a number of desirable features to the operation of the unit. A typical rack has a diameter of about 3 inches and can be divided into about l5 to 17 settings while still retaining adequate strength in the construction to lock against carpet tension loadings of 100 to about 800 pounds through most of the handle arc and up to about 1,100 pounds in the last of arc. Despite the small size of the rack, the location of the rack in one of the pivotable joints of the head results in a very strong locking mechanism. When the handle is in its most vertical position, the reaction force against the rack has the greatest lever moment about pin 110. As the arm is depressed and the load on the unit is increased by stretching of the carpet, this lever moment decreases in an inverse relationship to the load. Thus, the lever advantage of the lock increases with increasingload and a massive rack is not necessary. Another advantage of the arcuate rack is that the increment of extension or advance of the head with each increment of movement of the lever varies from a maximum value when the handle is upright to a minimum when the handle is fully depressed. In a typical unit this increment of advance can vary from about one-half inch to one-eighth inch. This is desirable for the most sensitive control since the maximum incremental advance occurs with the minimum tension on the carpet and when the carpet approaches its maximum stress, the incremental settings lessen.

FIGS. 5 and 6 illustrate a unit in which the ratchet means is carried by a separate ratchet rod. A conventional head and tail tube unit is modified to attach ratchet rod 126 which has a rack 128 on its upper surface. The head 130 is bored to receive rod 126, although, preferably, the trailing surface of head 130 is cast with a raised boss 132 to reinforce this bore. The rod can be threaded into the bore or secured in the bore with set screws. A ratchet housing 134 is secured to tube 136 by welding or by screws at a position that is aligned with rod 126. The housing has a central longitudinal bore to receive rod 126. Offset to one side and slightly below this central bore is a second longitudinal bore 138. The view shown in FIG; 6 is a sectional view along bore 138. At the rear of the housing 134 are two upright wings 140 that are bored to receive shaft 142 which extends between these wings. The wings define a slot 144 which extends into the central longitudinal bore and pawl 146 is mounted in this slot on shaft 142. Shaft 142 extends outwardly from wing 140 and supports, at its outboard end, lever 148. The outside surface of the wing is also slotted at 150 and this slot intersects bore 138 so that the lower end of lever 148 projects into this bore. A rod 152 which has a flat face 154 milled into its surface to provide shoulders fore and aft of the end of lever 148 is slidably mounted in bore 138. A hollow shaft 156 is secured to rod 152 and cable 158 is inserted into this shaft and welded thereto. The cable passes through sleeve 160 which is secured in bore 138 and spring means 162 is mounted in the bore between the end faces of sleeve 160 and rod 152. Pawl 146 is urged into engagement with rack 128 by compression spring 162 that biases lever 148 counterclockwise. The cable 158 is, of course, operative to move lever 148 in the opposite direction and thereby disengage the pawl from the rack.

FIGS. 7 and 8 illustrate a unit that has means for automatic engagement and disengagement of the pawl from the ratchet. The unit has the familiar components; tail tube 160, handle 162 and head 164 with tube 166. The link 168 is secured to pawl housing 170 which is attached to the tube 160 and to base 172 by screws. Housing 172 for the ratchet has a rim 174 that serves as a stop for tube 160 and sleeve 176 is mounted in this housing and projects forward to maintain alignment of shaft 166 and to enclose the rack 178 on shaft 166. This shaft is in sliding connection with the sleeve and the sleeve and housing 172 are bored at 180. A similar bore in pawl housing 170 is aligned with bore 180 and pawl 182 is positioned within this bore. The pawl has an end that mates to the grooves cut in rack 178. A shaft of lesser diameter than pawl 182 projects upwardly from the pawl; this can be a separate shaft that is fitted into the pawl or the pawl can be turned to a smaller diameter at its upper end. The upper rear corner of ratchet housing 170 is bored transversely and pin 184 can be placed in this bore. The pin supports lever 186 which is in the shape of a corner bracket with side webs 188 that are bored to receive the outboard ends of pin 184 so that the lever is pivotably mounted at the upper rear of housing 170. The top surface 190 of this lever projects over bore 180 and is bored to receive the and the upper face of pawl 182 is spring means 194 which urges the pawl into engagement with rack 178.

Twoapertures are provided in the top of h'ousing 170 in the form'of elongated bores 196 and 198. These serve as the points for pivotable attachment of link 168. As shown in FIG. 7, link 168 is pivoted from the forward aperture by pin 200. A second link member 202 projects rearwardly from this pin to the bottom of lever 186 where it is pivotably connected to the lever by pin 204.

The link member 202 andspring 194 cooperate with the elongated apertures 196 and 198 to provide for an automatic engagement and disengagement of the ratchet means whenever the handle 162 is operated. When the handle is moved downwardly to place tension on the carpet, the resultant forces seat pin 200 against the rear inside face of bore 196 or 198. This moves lever 186 rearwardly and releases the pawl so that spring 194 will urge it into engagement with rack 178. When the handle is raised, however, to release the tension on the carpet, the applied force will initially move pin 200 forward in the aperture and this initial movement will cause link member 202 to rotate lever 186 clockwise and retract pawl 182 from engagement with rack 178. A metal or plastic piston 167 can be secured to the end of tube 166 to retain alignment of this tube; particularly when it is fully extended as shown in FIG. 8.

The unit shown in FIGS. 7 and 8 can also be adapted for manual, rather than automatic actuation of the pawl means. This is shown in FIG. 8 where bore 210 is made longitudinally in the lower portion of housing 170. The bore is placed off center so that it does not intersect bore 180. A rod can be mounted in this bore and the rear end of the rod can be pinned to the bottom of lever 186 in place oflink member 202. A cable such as cable 158 shown in FIGS. and 6 can then be used to permit hand or manual operation of the pawl 182.

FIGS. 9 and 10 illustrate a ratchet and ratchet housingthat are similar to those shown in FIGS. l-3. In this assembly, however, an entirely circular cast housing 49 is employed. Tube 14 bears a similar rack 28 which fits into the housing. Tube 38 slips over the housing and bears against rim 51. Bracket 45 is attached to the assembly of tube 38 and housing 39 by screws 35 and 37. Screw 37 projects beneath the inner wall of the housing and its lower end engages groove 109 that lies along the top of tube 14. This groove and screw serve as the stop for the retraction and extension of tube 14 and also function to retain alignment of the tube-14. Bracket 45 has bores for two different lengths of link members such as 168 shown in FIG. 7, to convert existing stretchers.

The housing is bored at 59 to receive a rod, spring and cable assembly such as rod 152, spring 162 and cable 158 which are described with regard to FIGS. 5 and 6. A sleeve such as 160 shown in FIG. 6 is placed in the bore and the spring is biased against the end face of this sleeve to urge the pawl 31 into engagement with the rack.

The under surface of the housing 49 bears groove 57 which communicates with the longitudinal bore through the housing. A quarter section is cut out of the housing immediately behind groove 57 to form a partial annular recess 61. Pawl 31 is mounted in groove 57 on shaft 73 which extends between the sides of the housing at either side of the groove. Pawl 31 has an arcuate lever 77 which is attached to its rear surface and this lever fits into recess 61 with its free end projecting to the elevation of bore 59. A rod such as 152 projects into engagement with the free end of lever 77 and is connected thereto so that movement of the rod by cable 158 or by spring 162 will move the pawl out of or into engagement with the rack.

FIG. 11 shows the components of a kit useful for converting concentional stretchers to this invention. Elements that arent illustrated but that are included with such a kit include ratchet tube 14, cable 32 and hand lever 34. The tube 14 frequently can be slipped over the head shaft of conventional stretchers and secured thereto so that substantial modification of the head assembly for attachment of tube 14 is not necessary. The components illustrated are bracket 44, sleeve 42 and screw 46 which are used when the stretcher has a long link such as 22 shown in FIG. 1. When the stretcher has a shorter link such as 168 shown in FIG. 7, bracket 171 is employed and is secured to the ratchet housing by set screws 173.

Housing 48 and sleeve 53 are provided. As previously mentioned, sleeve 52 fits into housing 48 to serve as an alignment bearing for tube 14. Sleeve 53 preferably bears an inner bronze sleeve and serves as a bearing support for tube 14. Assembled to the housing are pawl 30 on shaft 72 which also bears lever 76 that projects between shoulders 69 and of rod 62. The rod fits into bore 58 and is biased rearwardly by spring 64 which is secured to housing 48 by pin 66. The opposite end of the rod is attached to cable 32. Pin 107 secures pawl 30 to shaft 72.

An alternative kit for converting conventional units to a ratchet controlled unit of the invention bracket 44, sleeve 42, screw 46 or bracket 171, together with a handle such as 112 shown in FIG. 4. Included with this kit would be an arcuate rack 106 spring 124, pawl l 14 and rod 122 such as shown in FIG. 4 together with the necessary pins and screws for the assembly of the unit as shown in FIG. 4.

Referring now to FIGS. 12 through 14, the preferred head assembly is illustrated. Plate 11, which is shown in FIG. 12 is formed of aluminum, magnesium, or alloys in which these metals are the principal components. The plate is generally triangular in shape and the ends can be rounded, as shown, or can be square. When the ends are square, additional end bearing edges are available for applying a tool such as a kicker stretcher to guide the head at an angle to the longitudinal axis of the stretcher.

At the trailing edge of the plate, shoe 96 is attached to the plate by bolts or screws 95 which rigidly secure the ends of the shoe to the plate. The plate is bored and tapped at 97, directly beneath the center of shoe 96. As shown in FIG. 13, screw 99 is turned into bore 97 so that advance of the screw raises the center of the shoe and retraction of the screw lowers the shoe. Tube 14 bears against shoe 96 and a fine degree of adjustment of the attitude of the head can be achieved. This shoe eliminates the tendency of the head to dip, a characteristic of most stretchers wherein the front of the head tilts downwardly when a load is applied withthe result that the front rows of teeth carry most of the applied load. The shoe' 96 provides a bearing surface that prevents this dipping.

A view through the assembly of the plate 11 and a preferred adapter 87 is shown in FIG. 13. The plate supports, on its under surface, rows of teeth 12. About 60 to 80 teeth can be placed in staggered positions along these rows at .about one inch centers and, preferably, the plate is formed with an angular boss 13 about each of the teeth. A typical plate has a thickness of about five-sixteenths inch and bosses 13 extend downwardly about one-eighth to one-fourth inch about each tooth.

It is preferred to cast the plate 11 with teeth 12 placed in the mold so that the teeth are cast directly in the plate. It has been found that this method provides several advantages over the conventional manufacture in which the cast plates are bored and the teeth are pressed into the bores. First, the manufacture is substantially simplified since the tedious boring and fitting of the teeth is avoided. Instead, the teeth are placed directly into the mold which can be a typical foundry sand mold and the molten metal is then poured into the mold and flows about the base of the shank of the teeth. The teeth can readily be placed in a single operation by using a holder or jig that aligns and places the teeth in a single step. Preferably, the upper ends of the shanks of the teeth are burred, knurled or surface roughened to aid in their retention in the cast plate. The contraction of the metal as it cools about the teeth will securely retain the teeth.

Another significant advantage is that the molding tempers the base of the teeth and results in a plate in which the teeth are more resilient and resistant to breaking than are the teeth of a conventionally manufactured plate. The teeth are commonly manufactured of hardened stainless steel to attain maximum hardness and strength at the pointed ends. Typically, the teeth are about one-eighth inch in diameter and are formed of 41-30 or 41 40 stainless steel alloys and are heat treated for maximum hardness. The teeth are also chrome or nickel plated after fabrication. As a result, the teeth are brittle and it is a common experience for teeth to snap or shear from the plate. The casting of the molten metal about the shanks of the teeth, however, tempers these shanks since the molten metal is cast at temperatures from I, l 00 to about 1,400 degrees F. and slowly cools to room temperature. This tempering or annealing renders the shanks more ductile and sudden impacts which will shear teeth from a conventional head will only bend the tempered shanks of the cast-inplace teeth. Any bent teeth can be readily straightened many times before the metal reaches its fatigue limit. Despite the tempering of the shanks, the sharp ends of the teeth retain all the original hardness and will wear equally to teeth that are conventionally placed in a plate after it has been cast. The tempering of the shanks extends a fraction of an inch, e.g., about one-eighth to three-sixteenths inch, beneath the cast plate and thus extends over the length at which the maximum bending and shear stresses are applied. It has been further found that the use of the raised bosses l3 greatly improves this tempering of the teeth shanks, probably by increasing the contact between the molten metal and the shanks, thereby providing a more complete annealing or tempering of the shanks.

As shown in FIG. 12, plate 11 is bored at 81 at a forward position on its mid-line and is bored and threaded at 83 and 85, which are at outboard positions. FIG. 13 shows that a bolt 89 is placed in bore 81. This bolt passes through sleeve 90, spring washer 91 and washer 92 and is secured by nut 93. This arrangement permits bolt 89 to turn in sleeve and permit plate 11 to swivel. The spring washer maintains a constant friction pressure between sleeve 90 and bolt 89. A coil spring could also be used. The adapter 87 is bored and threaded at 94 and bolt 95, which is attached to lever 82, isturned into this bore with its inner end terminating against sleeve 90. Rotation of lever 82 will lock sleeve 90 in bore 81 and hold plate 11 securely to adapter 87. The same elements are used in the adapter 79 shown in FIGS. 1 and 4, however, those adapters have an offset shoulder at one side and lever 82 is mounted on this shoulder.

The adapter is also bored. at 95 to receive the end of tube 14 which can be locked in the bore by a set screw, pin or threaded connection to the adapter. A base plate 84 with a polished under surface is preferably secured to the under surface of adapter 87 which is typically an aluminum casting. The adapter is bored transversely near its forward edge and the handle 97 is attached to the adapter by pin 20 which passes through this transverse bore. Preferably, the bore is positioned on or slightly below the centerline of tube 14 so that the maximum lever advantage of the handle 97 can be obtained and so that the bending stresses on tube 14 is minimized. By placing the handle pivot at or near the centerline of tube 14, the compressive loading on the head will not have any significant component in a vertical direction when the handle is fully depressed and substantially the entire load will be applied along the centerline of tube 14. This minimizes side forces on the rack and the alignment tube.

FIG. 14 is a sectional view along lines A-A' of FIG. 12. This shows screw 75 which is turned in tapped bore 85. The upper end of screw 75 is pinned to thumb nut 77 so that the rotation of nut 77 raises or lowers the screw in bore 85. Screw 75 bears a wide head that serves as a vertical stop for teeth 12. These screws which are positioned at each side of plate 11 limit the penetration of teeth 12 into the carpet. When the screws are properly adjusted to the thickness of the carpet, the teeth will project only to the set thickness and will not scratch or dig into the floor beneath the carpet. These height adjustment screws are optional features and can be eliminated, particularly when the adapter secures the stretcher handle at the leading edge of the head as in FIG. 13 and/or when shoe 96 is used. These latter features of construction insure that the leading edge of the head does not tilt but, instead, will retainthe head parallel to the floor so that all the teeth will uniformly engage the carpet.

The drawings illustrate a number of preferred embodiments including a reciprocating rack and an arcuate rack located in a joint of the power stretcher. Of the three possible locations for an arcuate rack, that shown in FIG. 4 is preferred since the rack is exposed to the greatest arc of movement between the handle and link. FIG. shows a cross sectional view of apreferred sliding lock which can be used between a power unit and the pole extension of a carpet stretcher. Preferably the power unit has a ratchet unit such as illustrated in FIG. 4 and the details of this ratchet are not repeated in FIG. 15. The tube 14 of the head assembly of the power unit projects into the sliding lock assembly and terminates therein with a collar or piston 167 which is secured to the tube by means such as threads, set screws, etc. This collar can suitably be Teflon or Nylon or a similar plastic having a low coefficient of friction.

The pole extension 220, which is shown at the opposite end of the. assembly, has a plate 222 secured thereto and a threaded bore 224 extends through the center of this plate. The pole extension is shown disconnected from stud 226. During use of the stretcher, the extension is slipped into tube 228 until it engages stud 226 and is assembled by turning it onto this stud.

Tube 14 is secured within the assembly by end sleeve 236 which has a forward rim 238 which serves as a stop for outer tube 228 and concentric tube 240. The forward movement of tube 14 is limited by spacer sleeve 234 which engages against the forward face of collar 167 when the tube 14 is moved to its most forward extension. A shaft 230 is slidably positioned in the assembly to telescope within tube 14 and a short sleeve 232 is secured to said shaft to serve as a bearing and to maintain alignment of the shaft within the assembly. The opposite end of shaft 230 bears plate 252 and boss 226, which as previously mentioned, is engaged in bore 224 of plate 222 when the stretcher is to be used. 7 The housing for the sliding lock assembly is formed by sleeve 236 and tube 240. End plate 244 is secured to tube 240 by set screws, threaded engagement, welding, etc. This end plate has a rim 246 which bears against the end of tube 240, a central bore for shaft 230 and a smaller bore in which is mounted pin 248. This pin is rigidly secured to plate 244 and projects a slight distance past the rear face of the plate. The pin is at the same radial spacing as bore 250 of plate 252 which is secured to shaft 230. Pin 248 serves as a rotational stop for plate 252 and thereby permits the pole extension 220 to be turned onto stud 226. In the illustration, shaft 230 is slightly withdrawn from the assembly and plate 252 is unseated from engagement with pin 248. Shaft 230 and pole extension 220 which is secured thereto by stud 236 are freely rotatable within the assembly.

The housing of the lock assembly is surrounded by outer tube 228 which slips over tube 240. This outer tube projects rearwardly of the housing a distance greater than the travel of shaft 230 and serves as an alignment sleeve for the pole extension 220. Bracket 44 such as that previously described with regard to FIGS. 1 and 11 is secured to tube 228 with set screws or welding. If desired, this attachment of bracket 44 can be reinforced by mounting the bracket on a short sleeve which is slipped about tube 228 and welded orlocked thereto. The bracket 44, as previously described serves as a pivotable connection between the link member such as 22 of FIG. 1 or 102 of FIG. 4 and the base of the power unit, i.e., the lock assembly shown in FIG. 15. Tube 228 is locked to the housing of the lock assembly by set screws, not shown, or similar means which permits the removable of the tube for servicing of the unit. When tension is applied to the carpet by depressing the stretcher handle, the load is transmitted through bracket 44 to tube 228 and then to the housing of the assembly.

The sliding lock of the assembly is similar to that described in FIG. 1 for the sliding attachment of pole 17. The lock comprises collar 256 and resilient means in the form of a compression spring 254. The spring is biased between the forward face of plate 244 and the rear face of collar 256. This collar has a finger 258 which projects into an aperture in tube 240. The collar is free to tilt about the detent of finger 258 in its aperture and spring 254 biases it forward. The lock permits the housing to be slipped or pulled forward .on shaft 230 when the stretcher handle is moved upwardly since collar 256 releases the shaft for extension of the unit. When the stretcher handle is depressed, shaft 230 is locked by collar 256 and can not retract in the housing. This occurs because the collar tilts slightly in a counterclockwise direction into a position where the lower rear edge and the upper forward edge of the hole in the collar bind against shaft 230. This action permits the lock unit to be used in a slip and lock action whereby the stretcher head can be pumped forward with the stretcher handle.

Collar 256 also has a manual release. Tubes 240 and 228 have an elongated aperture in their top wall opposite collar 256. The collar is bored and tapped and bolt 260 is turned into this bore. When bolt 260 is moved rearwardly against the tension of spring 254, collar 256 is removed from its clamping engagement with shaft 230. The assembly of shaft 230 and attached pole extension can then be moved freely in the collar. The collar 256 can also be unlocked to release shaft 230 by raising the handle of the stretcher unit so that tube 14 is retracted in the assembly and piston 167 dependent thereon bears against the forward lip 261 on collar 260 and forces it rearwardly against the tension of spring 254. In this manner, the power unit can be slid forward on the pole extension by simply grasping the handle, raising the handle and pulling the unit forward. The weight of the pole extension will retain it in place and permit the shaft 230 to slide through the unlocked collar 256.

The length of the extension which can be achieved by the unit can be varied over a wide range. The lock collar provides an infinite number of extendible settings and is preferably employed in combination with a ratchet unit shown in FIG. 4 to permit the locking of the handle at any position rather than req uiring that the handle be fully depressed. Generally, for most applications a slidable extension of from 5 to about 8 inches is adequate and will not require the use of an objectionably long housing assembly. Instead, it will be found that the unit is very-compact and can be used in very tight quarters such as in hallways, etc.

The slidable connection between the head and pole units has been described with reference to particularly preferred embodiments. Other embodiments can, of course be employed, e.g., collar 256 can be replace with several stamped rings, which will provide several tooth like gripping edges to engage shaft 230.

While the improvements of this invention have been described and illustrated by the presently preferred embodiments, it is not intended that the invention be unduly limited thereby. Instead, it is intended that the invention be defined by the elements and their obvious equivalents set forth in the following claims.

I claim:

1; In a hand powered carpet stretcher wherein a head bearing pins adapted to engage a carpet is assembled to one end of an elongated member having its opposite end in a joined sliding connection to a base member and one end of a lever member is in a joined pivoting connection to a forward portion of the assembly of said head and elongated member and, at an intermediate position along its length, is in a joined fulcrum connection to one end of a link member which has its opposite end joined in a pivoting connection to said base member, the improvement comprising ratchet means carried by one of said assembly, lever member and link member adjacent one of its joined connections, pawl means carried by the mating member of said joined connection and positioned opposite said ratchet means by a support permitting its movement into and out of engagement with said ratchet means and paw] actuating means linking said pawl means to said lever means whereby said pawl means can be moved into and out of disengagement from said ratchet means and said lever can be moved by a single-handed movement of an operator thereof.

2. The stretcher of claim 1 wherein spring means are carried by said mating member operative to bias said pawl means into one of said engagement and disengagement positions.

3. The stretcher of claim 2 wherein said ratchet means is carried by said elongated member as rack means and said pawl means is carried by said base member.

4. The stretcher of claim 3 wherein said link member is pivotably supported on said base member by pin means that is slidably mounted in an elongated aperture in said base member and said pawl actuating means comprises means linking said lever to said pawl whereby the sliding movement of said pin along said elongated aperture is operative to actuate said pawl means.

5. The stretcher of claim 3 wherein said ratchet means is telescopingly mounted within said base member.

6. The stretcher of claim 2 wherein said pawl actuating means comprises cable means extending from said pawl to the free end of said handle.

7. The stretcher of claim 3 wherein said base member carries a tubular sleeve member that projects over and is co-axial with said elongated member and said rack means carried by said elongated member is fully within said sleeve member at all extensions of said s 'i' h stretcher of claim 3 having stop means comprising a groove in one of said elongated and base members and a detent means operative therewith carried by the other of said members to limit the travel of said elongated member in said base member.

9. The stretcher of claim 3 wherein said head is carried by shaft means that is in sliding connection with said base member and said elongated member bearing said rack means is in sliding connection with a pawl housing carried on said base member and supporting said pawl means.

10. The stretcher of claim 3 wherein said base member comprises a tubular member and a sleeve member mounted within the forward end of said tubular member with said elongated member projecting through the central passageway of said sleeve and bearing, at its free end and behind said sleeve, a piston member that bears on the inside surface of said tubular member and thereby aids alignment of said elongated member in said base member.

11. The stretcher of claim 3 wherein said base member comprises a tubular member and a housing secured to the forward end thereof and wherein said pawl means is mounted within said housing.

12. The stretcher of claim 11 wherein said housing comprises a sleeve member having a partial section removed therefrom at a position intermediate its ends to define a partial annular recess and wherein said pawl means is pivotable secured to said sleeve member within said recess. 

1. In a hand powered carpet stretcher wherein a head bearing pins adapted to engage a carpet is assembled to one end of an elongated member having its opposite end in a joined sliding connection to a base member and one end of a lever member is in a joined pivoting connection to a forward portion of the assembly of said head and elongated member and, at an intermediate position along its length, is in a joined fulcrum connection to one end of a link member which has its opposite end joined in a pivoting connection to said base member, the improvement comprising ratchet means carried by one of said assembly, lever member and link member adjacent one of its joined connections, pawl means carried by the mating member of said joined connection and positioned opposite said ratchet means by a support permitting its movement into and out of engagement with said ratchet means and pawl actuating means linking said pawl means to said lever means whereby said pawl means can be moved into and out of disengagement from said ratchet means and said lever can be moved by a single-handed movement of an operator thereof.
 2. The stretcher of claim 1 wherein spring means are carried by said mating member operative to bias said pawl means into one of said engagement and disengagement positions.
 3. The stretcher of claim 2 wherein said ratchet means is carried by said elongated memBer as rack means and said pawl means is carried by said base member.
 4. The stretcher of claim 3 wherein said link member is pivotably supported on said base member by pin means that is slidably mounted in an elongated aperture in said base member and said pawl actuating means comprises means linking said lever to said pawl whereby the sliding movement of said pin along said elongated aperture is operative to actuate said pawl means.
 5. The stretcher of claim 3 wherein said ratchet means is telescopingly mounted within said base member.
 6. The stretcher of claim 2 wherein said pawl actuating means comprises cable means extending from said pawl to the free end of said handle.
 7. The stretcher of claim 3 wherein said base member carries a tubular sleeve member that projects over and is co-axial with said elongated member and said rack means carried by said elongated member is fully within said sleeve member at all extensions of said assembly.
 8. The stretcher of claim 3 having stop means comprising a groove in one of said elongated and base members and a detent means operative therewith carried by the other of said members to limit the travel of said elongated member in said base member.
 9. The stretcher of claim 3 wherein said head is carried by shaft means that is in sliding connection with said base member and said elongated member bearing said rack means is in sliding connection with a pawl housing carried on said base member and supporting said pawl means.
 10. The stretcher of claim 3 wherein said base member comprises a tubular member and a sleeve member mounted within the forward end of said tubular member with said elongated member projecting through the central passageway of said sleeve and bearing, at its free end and behind said sleeve, a piston member that bears on the inside surface of said tubular member and thereby aids alignment of said elongated member in said base member.
 11. The stretcher of claim 3 wherein said base member comprises a tubular member and a housing secured to the forward end thereof and wherein said pawl means is mounted within said housing.
 12. The stretcher of claim 11 wherein said housing comprises a sleeve member having a partial section removed therefrom at a position intermediate its ends to define a partial annular recess and wherein said pawl means is pivotable secured to said sleeve member within said recess. 